code: def get_sentence_by_tree(tree):
      if tree is None:
          return ""
      if tree.is_leaf():
          return tree.word
      left_sentence = get_sentence_by_tree(tree.subtrees[0])
      right_sentence = get_sentence_by_tree(tree.subtrees[1])
      sentence = left_sentence + " " + right_sentence
      return sentence.strip()
  
imports: import logging
  import os
  import pickle
  from collections import Counter
  import numpy
  import torch
  from torch.utils import data
label_desc: Use image node_id 6 for calling a global function with example usage: get_sentence_by_tree(tree) and returns: sentence, str, tree